The invention relates to a slide ring seal for sealing a gap between a rotatable and a non-rotatable machine part, comprising at least one static seal ring to be fastened to the non-rotatable machine part and provided with a slide ring and at least one counter ring to be attached to the rotatable machine part and provided with a slide ring, the static seal ring and the counter ring being arranged to be fastened so that the slide surfaces of the slide rings are pressed tightly against each other.
Slide ring seals are known from various technical fields. They are used, e.g., in gearboxes, pumps and other such devices to prevent liquid from leaking from the contact points between a rotatable machine part and an immovable machine part. There are two types of axially sealing slide ring seals. Single-acting seals comprise two rings rotating with respect to each other, one of which is attached to and sealed on the rotatable machine part and the other is attached to and sealed on the immovable machine part. The rings are pressed into sealing contact with each other by means of slide surfaces formed thereon. In single-acting slide ring seals, the lubrication is wholly carried out by means of a liquid to be pumped, wherefore single-acting seals are not suited for use with liquids that contain mechanically wearing particles. In their simplest form, double-acting seals are formed by two single-acting seals which define therebetween a space into which a separate sealing liquid is introduced, mainly for lubricating the slide surfaces of the rings rotating with respect to each other.
A disadvantage of prior known slide ring seals is that they are formed by several different parts, such as a body, a seal ring or seal rings, a counter ring or counter rings, a spring, springs or a bellow, auxiliary seals, etc. As a result of the great number of the requisite parts, the seal is complicated in structure, which complicates the storing of replacement parts, the production control and the assembly of the seals. Moreover, the complexity also often makes the seal unreliable, because, simultaneously as the number of parts increases, disturbances become more likely.
Known solutions include the slide ring disclosed in Finnish Patent Specification No. 61,558. This known seal solution comprises eight separate and dissimilar parts, excluding O-rings, screws and springs, namely a counter ring, a seal ring, a body, another seal ring, another counter ring, a supporting ring, a press ring and a flange. In addition to these parts, at least 8 to 10 O-rings, 9 to 10 screws and 10 to 20 separate springs are needed. Accordingly, 40 to 50 parts, of which 20 to 30 are unlike, have to be handled during the assembly of the seal.
Attempts have been made to achieve improvement in this matter by standardization, e.g. DIN 24960. Thereby, the counter rings, for instance, are made similar. The seal itself, however, may be very complicated.